Charge forming device



Sept. 13, 1932, c. H. KINDL CHARGE FORMING DEVICE Filed Nov. 14, 1928 Patented Sept. 13, 1932 A STATES PATsNToFFicE CARL H. KINDL,`OF DAYTON, OI-IIO, ASSIG-NOR, BY MESNE ASSIGNMENTS, T DELOO PRODUCTS CORPORATION, orr

DAYTON, OHIO, A CORPORATION OF DELAWARE CHARGE FORMING DEVICE Application iled November 14, 1928. Serial No. 319,362.

' rlhis invention relates to charge forming devices for internal combustion engines and VCII more particularly to the type of charge forming Vdevice which comprises a plurality of primary fuel mixing chambers,fonefor each int-aire port of the engine and cooperating respectively with a plurality yof secondary mixing chambers locatedadjacent the engine intake ports and receiving fuel air mixture from pipes connected'with the'primary carburetors, and receiving air when required through branches of an air manifold having a single air inlet for supplying air to all the secondary mixing chambers. A common fuel reservoir supplies liquid fuel to all the primary mixing chambers.

Examples of charge forming devices of this character vare disclosed in the copending applications of Wilford H., Teeter, Serial. No. 221,372, filed September 22, 1927, and of Wilford l-l. Teeter and Fred E. Aseltine, Serial No. 221,371, filed on the same'date, and which have matured into Patents 1,819,- 526 and 1,819,495 respectively both granted Aug. 18, 1931. i j

Various means are provided 'in charge forming devices of thischaracterl heretofore known, such for instance as thosefdisclosed in the above applications, to control the f iow of air and fuel under various operating conditions for'the purpose of securing at all times a. mixture having the desired fuel and air ratio. Certain of these flow proportioning devices are made necessary because the air flowing through the primary mixing chambers moves past the fuel kjetsv therein at such high velocity that it creates a velocity head at the jets which is the force effective to cause a flow of fuel therefrom. Unless some means be provided to prevent the increase of the velocity head, it is found that it builds up very rapidlv o-n increase of enginespeed, resulting inthe formation of too rich a mixture to be properly combustible, and unsatisfactory engine operation. Since the velocity head is a variable thing depending .on severall different factors, it follows that the excessof fuel inthe mixture which depends Von the velocity headis also variable and it has been found veryv 'ing diflicult'to control the effect of the velocity head on the fuel flow or to secure the desired iiowY of fuel under all operating conditions.

It is the principal object of the present invention to provide a charge forming device in which the effect of velocity head on the fuel flow is substantially eliminated, and more specifically, ing device in which the flow of fuel is controlled by the static suction within said' charge forming device as determined'by the means which controls the admission of air thereto.

According to the present invention, this is accomplished by providing a mainair cham ber having unrestricted connection with both the primary mixture passages and the secondary air passage and a spring held valve for contro-lling admission of air to said air chamber. The fuel jets, instead of projectmunicate directly with the air chamber so that the suction maintained at the said jets to provide a chargeV forminto the primary mixture passages com- Y is the same as that of the air chamber. VIn

a device of this ycharacter the jets can be calibrated in accordance with the air valve Spring to admit the necessary amount of vfuel 'to form a mixture of the desired proportions at all times. y

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein apreferred embodiment ofone form of the present invention is clearly shown.

In the drawing:

Fig. 1 .is a vertical longitudinal section through a charge forming device embodying the present invention and showing one outlet branch of the manifold.

Fig. 2 is a fragmentary section on the line 2-2 of Fig. 1.

Fig. 3 is a horizontal section on the line 3-3 of Fig. 1.

Fig.4 is a fragmentary section showing the outlet of the pump.

The device disclosed herein comprises a main `air manifold 10 having three outlet branches, the middle branch 12, being shown herein. Each of these branches communi- Cates with one of the intake ports 14 of a multicylinder engine. These branches are each provided with an attaching flange 16 for securing the manifold to the engine block in the usual manne-r. Adjacent the inlet of the manifold is provided a flange 18 to which the main carburetor unit is adapted to be attached as shown in F ig. 1.

The carburetor unit comprises a main housing 2O having an attaching flan-fre 22, adapted to be secured to flange 18 by screws 24. An air inlet horn 26 is secured in position to register with an o1 ening in the upper wall of the housing 2O in any suitable way. A casting 28, having certain dash pot chambers and fuel passages formed therein, is secured by screws to the lower wall of the housing 20 and a sheet metal fuel bowl 30 is held tight against a shoulder 32, formed on a skirt 34 depending from the housing 20, by any suitable means. Fuel is conducted from a main source of supply to the fuel bowl through a conduit not shown here-in and the flow of fuel to the bowl is controlled by a float 36 operating in the usual. manner to maintain a substantially constant level of fuel therein.

Fuel flows from the bowl 30 to a plurality of primary fuel nozzles 38 which project into a main air chamber 40, the construction of which is fully described hereinafter. The fuel conduit between the fuel bowl and the nozzles comprises a vertical fuel passage 42 communicating at its upper end with a horizontal fuel canal 44, which connects with each of the nozzles through orifices 46. Fuel is admitted to the passage 42 at low speeds through a fixed metering orifice 48 and at high speeds additional fuel is admitted through an orifice 50, controlled by a valve 52, in the manner set forth in the above mentioned applications.

Fuel is lifted from the fuel bowl through the above described fuel passages and nozzles 38 by the suction in the air chamber adjacent said nozzles. Glosing movements of the throttle cause a reduction in suction in said air chamber which might permit the fuel column to drop sufficiently to cause a temporary fuel starving of the engine unless means were pr vided to prevent it. For this purpose a check valve 54 is provided in an enlarged chamber 56 at the junction of channels 42 and 44, and on reduction of suction in the air chamber, seats on a rib 57 projecting upwardly from the bottom of such chamber, thus preventing downward flow of fuel,

Each primary fuel nozzle is provided with a main fuel outlet 58 in the top of the nozzle and a secondary fuel outlet comprising two orifices 60 and 62 near the bottom of the vertical wall of the nozzle. At relatively high speeds, the mixing chamber suction is enough to lift fuel from the main outlet as well as from holes 60 and 62. During idling or operation at very low speeds under load, however, the suction is suthcient to lift fuel only to some pointbetween the top of the nozzle and orifices 60 and 62, fuel flowing from these orifices by action of gravity. Each nozzle is provided with a restricting fuel metering ori* fice 63. Y

The lower part of the air chamber is divided by partitions 64 into three separate spaces 66 which may be termed primary mixing chambers and which communicate with three primary mixture passages 68 formed in the lower part of the main housing 20. These passages 68 are parallel to each other and close together as indicated in Fig. 2, and when the carburetor unit is secured to the manifold, these passages register with conduits which convey the primary mixture to the secondary mixing chambers, as fully described in the above copending applications.

A single throttle valve 70, which ext-midell across all the primary mixture passages, controls the flow therethrough and is provided with grooves Z2 which register with the mixvture passages. This throttle is operated by means fully disclosed in the above copending applications and which forms no part of the present invention. The middle primary mixture passage connects with a tube 74 fixed in the manifold branch 12, which conveys the primary mixture to the secondary mixing chamber in that branch of the manifold.

Substantially all the air entering the carburetor flows through the air horn 26, controlled by a main air valve 76, normally held against a seat 78 by a spring 80, received between the valve and a flange 82, projecting from the sleeve 84, slidably mounted on a stationary guide sleeve 86, fixed in the hcusing 20, and serving as a guide for the stem 88, to which the air valve is secured.

Vhen it is desired to choke the carburetorv to facilitate starting of the engine, the flange 82 is adapted to be lifted, by means not shown herein, until Vthe upper end of the sleeve 84 engages the valve to hold it against its seat. Sufficient air to carry the starting fuel from the rnozzles to the intake ports is admitted through small ports formed in the wall of the main housing 20, as shown in Fig. 1.

The valve 76 admits air to the main air` j,

chamber 40, hereinbefore referred to, from `which air flows through the spaces 66 tothe primary mixture passages 68 and to secondary mixing chambers, hereinafter described, through a secondary air passage 92, which connects with the inlet of the manifold 10. An air throttle 94, secured to a shaft 96, controls the flow of air through the passage 92, said throttle being operated by the same operating mechanismV as the throttle 70, in 3* the manner fully set forth in the copending applications above referred to.

On opening of either or both of the throttle valves, the suction in the air chamber 92 is increased and the air lvalve 76 is opened against the force -ofits closing spring to admit. additional air and increasethe quantity of mixturev supplied to the engine. The opening of the valve must be retarded to some extent, however, to prevent admission of sufficient air to lean the mixture. A dash pot is provided to` accomplish'this result and to prevent fluttering of the valve, comprising a cylinder and a piston 102, secured to the lower end of the air valve stem 88 in any desirable manner, as by a nut 104. The dash pot may be of any desired construction so far as thisV invention is concerned. A. pump may be provided to inject additional fuel into the mixture on opening of the throttles in order to enrich the mixture to some extent for acceleration. The dash pot, previously described, comprises the pump andis provided with a fuel `delivery conduit extending from the dash pot cyl'- ind-er to the air intalre horn. This delivery conduit is provided with a checl'r valve 112 to prevent return cylinder on upward movement of the piston 102. rThe details of constructionVV of this pump are in no way material to the present invention, but are fully disclosed in cepending application Serial No. 221,372. Further,

jondary mixing chamber.

`cured to the engine block,

this particular pump is merely shown for illustration purposes and any other suitable form ofr pump may be employed. f

Each primary mixture conduit, vpreviously described, delivers primary mixture to a sec- There are three of these chambers which are identical in construction and each of whichc'omprises a Venturi tube positionedso that the point of greatest suction thereiny is immediately adjacent the outlet end of the primary mixture tube which is associated Ytherewi h. Each venturi is provided with an-external rib 122 which is clamped, when the manifold is sein a recess 124, between shoulders 126 and 128 on the manifold and the engine block respectively. The Venturi tubes increase the velocity of the air flowing'past the ends of the primary mixture conduits and insure a relatively high velocity Aof flow through said conduits under all operating conditions.

'.l`he device above described with the excep tion of the arrangement of vthe fuel jets pro-- jecting into the main airchamber 40, and the direct connectionof the primary mixture passages 68 with such chamber vis substantially the same general construction'as shown in the two applications above referred to and ther earlier forms of this type of charge forming device. As has been previously'set forth, the lower part of the mainfair chamber 92, according to the present invention, is divided into three separat-e spaces or channels 66 by means of division plates 64cast integral with the housing 20 and projecting upwardly from the bottom of the chamber 40. lThese flow of fuel to the dash pot fasindicated in Fig. bility of any fuel above described increase spaces 66 are open at the top having unrestricted communication with the air chamber. Thev fuel nozzles 38 projectupwardly `into these spaces so that the suction maintion, as determined by the air valve spring 80. Having unrestricted connection with Athe Y air chamber, the velocity of flow past the nozzles through the spaces 66 never increases to such an extent that a velocity head is formed at the nozzles, the suction at said nozzles being the static suction of the air chamber under all operating conditions.r

A plate 130 extends across'all ofl thefuel nozzles 38, being secured at its ends tol lugs 182 projecting inwardly fromthe'wall of the main housing'by means of screws 1311-. This plate prevents fuel from the nozzles passing upwardly intoV the currentof air entering the air passage 92 from chamber ll0, At its posterior edge', this plate is provided with slots 186 engaging the partitions 64, and the portions 136 of the plate lying between the partitions are bent downwardly,

being carried upwardly into the passage 92by any current of air passing by the nozzles and upwardly into said passage.

Whilethe means for operating the two throttle valves constitutes no part of the present invention, the modeof operation of these valves will be briefly set forth in order to enable the present invention to be better understood. At engine speeds up to approximately that speed which corresponds 'to a vehicular speed of 2O miles per hour on a level, only the primary throttle 70 is opened and the'primary mixture is of proper com- 'sufficient 1n quantif bustible proportions and ty to meet the requirements of the engine. At speeds' above the speed referred to, the velocity of flowl through the primary mixture passages would increase very rapidly creating a velocity head at the fuel jets when said jets terminate in the saidpassages. To prevent such action, the tl'irottle operating mechanism is so designedthat the throttle 94 begins to open at approximately the speed above referred to, admitting air to the'secondarymixing chambers and preventing the in velocity of flow through the primary mixture passages.

It has been found, however, that by open; ing the throttle'as above described, the difficulties due to the presence of a velocity ef feet 'at the nozzles are not entirelyeliminated and to avoid these difficulties the nozales according to the present invention are constructed to communicate directly with the main air chamber, as previously described, so that the velocity head at said nozzles is entirely eliminated.l

The advantageous results producedv by `the 1, to prevent the possi'-` LMO .builds vabove referred to.

Owing to the presence of a velocity head at the fuel jets in such devices the metering jets which determine the fuel flow are calibrated somewhat smaller than they should be to give a fuel mixture ratio of 123%d to 1 proper for medium speed. Up to an engine speed of approximately 1000 R. P. M., which is equivalent to a vehicular speed of 20-25 miles per hour, the velocity head increases slowly and produces a flow which is approximately correct to give the desired mixture ratio.

At higher engine speeds the velocity head up so rapidly that the fuel mixture .becomes entirely too rich unless means are provided to reduce the velocity effect on the jets. To do this the secondary throttle corresponding to throttle 114 of this device is timed to begin opening at an engine speed of about 1000 R. P. M. Owing to the large diameter of this throttle and consequent rapid increase in volume of air flowing past the throttle per degree of rotation, the velocity of air flowing past the jets is very rapidly lowered after the air throttle begins to open, the velocity head being practically eliminated at a little more than 1500 R. P. M. Since the fuel flow is determined by velocity head and the jets are calibrated to give a proper feed of fuel as the velocity head increases up to 1000 R. P. M., the reduction in velocity head at higher speeds causes so great a reduction in fuel flow that the mixture becomes too lean to be properly combustible. This necessitates an additional flow of fuel which is provided by opening a needle valve similar to the valve and permitting fuel to flow through an auxiliary fuel passage.

This valve is opened by means of a cam, the contour of which is designed, in the above mentioned earlier applications, to begin opening the fuel valve at approximately 1000 R. P. M. and to continue opening said valve to admit just enough additionalfuel to compensate for the loss in suction on the fuel jets due to reduction in the velocity head effective thereon.

In order to secure a fuel mixture of the desired proportions, the two throttles must be accurately synchronized, not only with relation to each other, but also to the needle valve. The cam which lifts the needle must be correct in contour, must be accurately located with reference to its follower and the latter must be also of exactly the right size and located in the right position. Since it is attempted to correct the velocity head which is a variable and unstable force by a mechanically operated means, it is dificult to attain the synchronization of operation referred to, and if such synchronization is secured it will be disturbed by wear or by dimensional variations, or by any of the parts becoming loose.

By eliminating the velocity head at the jets and employing metering jets calibrated to permit flow of fuel necessary to give a fuel mixture of 151/2 to l when the fuel flow is governed by engine suction as determined by the spring' held main air valve, the variation in fuel flow on opening of the air throttle will disappear and there will be no need to open the needle valve to admit additional fuel except for full throttle operation. Therefore, the need of accurate timing of operation of the two throttles relative to each other or to the needle valve will disappear.

`While the form of embodiment o-f the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A charge forming device for internal combustion engines comprising a main air supply chamber, a plurality of primary mixture passages communicating with said air supply chamber, partition plates in the air supply chamber separating said chamber into a plurality of individual spaces, each of which communicates with one of said mixture passages, a secondary air passage also communicating with said air chamber and supplying additional air for admixture with the primary mixture, and a plurality of fuel jets one of which communicates directly with each of said tion of the air chamber is effective to cause a flow of fuel from each of said jets.

2. A charge forming device for internal combustion engines comprising a main air supply chamber, a plurality of primary mixture passages communicating with said air supply chamber, partition plates in the air supply chamber separating said chamber into a plurality of individual spaces, each of which communicates with one of said mixture passages, a secondary air passage also communicating with said air chamber and supplying additional air for admixture with the primary mixture, a plurality of fuel jets, one of which communicates with each of said spaces, whereby the static suction of the air chamber is effective to cause a flow of fuel from each of said jets, and a single means for preventing any of the fuel being carried into said secondary air passage.

3. A charge forming device for internal combustion engines comprising a main air supply chamber, a plurality of primary mixture passages communicating with said air supply chamber, partition plates in the air spaces, whereby the static sucsupply chamber separating said chamber into a plurality of individual spaces, each of Which communicates vvithone of said mixture passages, a secondary air passage also communicating with said air chamber and supplying additional air for admixture With the primary mixture, a plurality of fuel jets, one of which communicates with each o-f said spaces, whereby the static suction of the air chamber is effective to cause a flow of fuel from each of said jets, and a single baille plate positie-ned above all of said jets to prevent the fuel issuing from said jets reaching the secondary air passage.

el. A charge forming device for internal combustion engines comprising a primary mixture passage, a secondary mixing chamber into which said mixture passage delivers a primary mixture of fuel and air, a secondary air passage for supplying air to the secondary mixing chamber, an air chamber having an inlet communicating With the atmosphere and connecting directly with both the primary mixture passage and secondary air passage, means for 'supplying fuel to the primary mixture passage comprising a nozzle directing a jet of fuel into said last mentioned chamber, and a baffle so positioned in the air chamber that the fuel issuing from the nozzle impinges thereon and is prevented from passing into the secondary air passage.

5. A charge forming device for internal combustion engines comprising a primary mixture passage, a secondary mixing chamber into which said mixture passage delivers a primary mixture of fuel and air, a secondary air passage for supplying air to the secondary mixing chamber, a chamber having an inlet communicating With the atmosphere and connecting with both the primary mixture passage and secondary air passage, means for supplying fuel to the primary mixture passage comprising a nozzle directing a jet of fuel into said last mentioned chamber, and a above the nozzle to prevent the fuel issuing therefrom from passing into the secondary air passage.

6. A charge forming device for an internal combustion engine comprising a primary mixture passage, a secondary mixing chamber into which said mixture passage delivers a primary mixture of fuel and air, a secondary air passage for supplying air to the secondawry mixing chamber, a chamber having an inlet communicating With the atmosphere and connecting With both the primary mixture passage and secondary air passage, means for supplying fuel to the primary mixture passage comprising a nozzle directing a jet of fuel into said last mentioned chamber, a baffle plate positioned immediately above the nozzle to preventthe fuel issuing therefrom from passing into the secondary air baflie plate positioned immediatelyV passage anda downwardly projecting lip at the posterior edge of said baffle plate.

7 A charge forming device for internal combustion engines comprising va primary mixture passage, a secondary mixi g chamber into which said mixture passage delivers a primary mixture of fuel and air, a secondary air passage for supplying air to the secondary mixing chamber and positioned above the primary mi having an inlet communicating With the atmosphere and connecting With both the primary mixture passage and the secondary air passage, means for supplying fuel to the primary mixture passage comprising a nozzle directing a jet of fuel into said last mentioned chamber and a substantially horizontal baiiie positioned in said chamber above the nozzle to prevent the spraying of fuel therefrom to a sufcient height to be carried into the sec-` ondary air passage.

In testimony whereof I hereto affix my signature.

CARL H. KINDL.

xture passage, a chamber 

